1. Technical Field
The present disclosure relates to a two-cylinder hermetic compressor used for an outdoor unit of an air conditioner and a freezer.
2. Description of the Related Art
Generally, a hermetic compressor used for an outdoor unit of an air conditioner and a freezer includes an electric motor unit and a compression mechanism unit in a sealed container. The electric motor unit and the compression mechanism unit are connected to each other by a shaft, and a piston attached to an eccentric portion of the shaft revolves with the rotation of the shaft. A main bearing and an auxiliary bearing are mounted on both end surfaces of a cylinder having the piston provided therein, and the shaft is supported by the main bearing and the auxiliary bearing. Generally, one-cylinder hermetic compressor is often used.
On the other hand, PTL 1 (Unexamined Japanese Patent Publication No. 2001-271773), PTL 2 (Unexamined Japanese Patent Publication No. 2008-14150), PTL 3 (Unexamined Japanese Patent Publication No. 2012-52522), and PTL 4 (Unexamined Japanese Patent Publication No. 2012-167584) disclose a two-cylinder hermetic compressor.
Meanwhile, in comparison to a one-cylinder hermetic compressor that has conventionally been used most often, the two-cylinder hermetic compressor disclosed in PTL 1 to PTL 4 has a shaft provided with two eccentric portions, wherein a sliding loss of the eccentric portions can be reduced by decreasing the outer diameter and the height of the eccentric portions.
However, due to the reduction in the outer diameter and height of the eccentric portions, the sliding areas of the eccentric portions are undesirably decreased, which entails a problem of an increase in maximum stress on the eccentric portions.